Microlithographic Projection Lens Imaging Scale Correction
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Solution Overview
Problem
Conventional microlithographic projection exposure systems experience image fading due to scale corrections in the scanning direction, leading to a 'smudged' wafer image, as they attempt to correct wavefront aberrations and imaging scale errors.
Innovation Solution
A microlithographic projection exposure apparatus with a manipulation device that independently adjusts the imaging scale in multiple directions, allowing for asymmetric corrections by controlling the projection lens's imaging scale in the scanning and transverse directions, and a control apparatus that adapts scanning movements to match the imaging scale to the effective imaging scale produced by different scanning speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the imaging scale is corrected by adapting the scanning movement profiles of the substrate stage and mask stage, then the imaging scale error is corrected, but the wafer image becomes smudged or faded
Solution Approach 1:
The correction of imaging scale is segmented into two independent directional components: scanning direction correction and transverse direction correction. The manipulation device independently adjusts the imaging scale in the scanning direction (y-direction) and transverse direction (x-direction) separately, allowing precise correction without causing image fading. This segmentation enables the system to correct scale errors in each direction without the harmful side effects that occur when a single coupled correction is applied.
Solution Approach 2:
The invention applies asymmetric correction by allowing different correction factors for the scanning direction and transverse direction. The manipulation device can apply a first correction factor in the scanning direction and a second correction factor in the transverse direction, where these factors are independently determined. This asymmetric approach optimizes correction for each direction based on specific requirements, preventing the image fading that occurs with symmetric (coupled) correction of scanning movement profiles.
2Manufacturing precision
If a projection lens with minimal wavefront aberrations is used, then imaging precision is improved, but additional manipulators and control complexity are required to correct aberration characteristics
Solution Approach 1:
The manipulation device is designed with multi-functionality to perform both wavefront aberration correction and imaging scale correction using the same optical element manipulation capabilities. By adjusting the position, tilt, or shape of optical elements within the projection lens, the device simultaneously corrects aberrations and controls imaging scale in both scanning and transverse directions. This universal approach avoids the need for separate dedicated mechanisms for each correction type, reducing overall system complexity.
Solution Approach 2:
The invention utilizes parameter changes of optical elements (position, tilt angle, curvature) to achieve both aberration correction and imaging scale adjustment. By dynamically changing these physical parameters of the optical elements through the manipulation device, the system can adaptively correct wavefront errors and control imaging scale without requiring additional complex subsystems. The same parameter adjustments serve multiple correction purposes.
Data Source
AI summary
A microlithographic projection exposure apparatus is configured to move a substrate stage in a scanning direction during the exposure process. The apparatus includes a projection lens for imaging mask structures onto a substrate during the exposure process with a manipulation device configured to change an imaging scale of the projection lens in at least two directions independently from one another. The apparatus also includes a control apparatus configured to perform different corrections of the imaging scale by way of suitable control of the manipulation device in the scanning direction and transversely to the scanning direction.